Patent GB-196347-A (GB)
Title: Improvements in or relating to hydraulic apparatus and mechanism for use in connection therewith
IPC: B23D15/14
Filed: 1922-01-18
Abstract: 196,347. Smith, E. M. Jan. 18, 1922. Presses, cylinder - and - piston: limiting stroke of press; governing and controlling; producing part of stroke of hydraulically; relief and safety devices for; ram retracting devices; pressure-producing apparatus; working valves. - Hydraulic presses for baling, moulding, metalworking, operating ordnance, ore crushing, &c., comprise a ram, a liquid reservoir, a pump or pumps driven by hand or power, and means for automatically terminating the power stroke of the ram at any desired point and for returning the ram to its initial position. Handoperated controlling means, means for stopping the ram on the attainment of a pnedetermined pressure, and special pump-operating mechanism may also be provided. In the form shown in Fig. 1, the pump H constantly supplies liquid to the cylinder of a retracting ram D, the cylinder A of the main ram B being connected to the pump outlet or to the reservoir C through passages controlled by valves H<1>, H<2>, which are spring-controlled and operated by a cam surface on a slidable bar G reciprocated by a striking arm F<3> on a spring-controlled quadrant F. The quadrant is oscillated by means of adjustable stops B<4>, B<5> on a rod B<3> connected to the rams, so that at the ends of the stroke the valves are suddenly reversed. Tappet-operated valves H', D<3> relieve the pressure in the main and retracting cylinders at the ends of stroke in the event of the automatic reversing-mechanism failing, and a hand-operated valve H<5> allows the main cylinder to be put into communication with the reservoir C at any time. During the power stroke, any liquid that may have leaked past the main ram is returned to the reservoir through a valve H<8>. In a form especially suitable when the pump is manually operated, the rod of the main ram may be provided with a port through which the pressure in the ram cylinder is relieved at the end of the power strode. In the construction illustrated in Fig. 2, the main ram B is formed with a cylinder receiving a piston carried by a post depending from the bottom of the reservoir C, and the valve-reversing mechanism is disposed in the reservoir. At the commencement of the power stroke, the valves allow liquid to pass through passages I<2>, I<3>, and the lowering of the ram draws liquid into the cylinder A from the reservoir through a passage I<4> and non-return valve. When the ram B leaches the work, the pressure increases and opens a valve to allow pressure liquid to pass to the cylinder A. At the end of the power stroke, the automatic valve gear opens the cylinder A and the passage I<2> to exhaust, and the ram is returned. A further form has a pilot valve H<12>, Fig. 3, which is opened by an adjustable stop B<6> to relieve the pressure. in the cylinder A, after which the main exhaust valve J can be opened by hand and the ram returned by a spring B'. In a modification of the latter form, the pump delivers through a passage H<x>, Fig. 4, into the cylinder D<1> of a retracting ram. When the pilot valve has been opened, the band-lever J<2> may be operated to cut off communication between the cylinders D<1>, A and put the latter cylinder to exhaust. In another form so constructed that the power stroke may be stopped either at a predetermined point or on th occurrence of a predetermined pressure, the pump is driven by one of the eccentrics L<1>, L<2>, L<3>, Fig. 7, on an axially adjustable shaft, and delivers into a conduit Z<5>, Fig. 6, leading to the cylinder A, and also connected to a conduit Z<6> normally closed by a valve M<1> acted on by the lever N held down by an adjustable spring N<3>. On the occurrence of a predetermined pressure, the valve M<1> is lifted and the liquid acts through a plunger M<3> and lever M<5> to move a spring-pressed trigger M<7> out of engagement with one end of a lever O, the spring-pressed exhaust valve O<3> being then free to open, and the ram is returned by a spring. As the lever O moves, a pin O<6> opens a valve M<10> to relieve the pressure, and a spring M<12> returns the plunger M<3> to its original position. When the ram reaches its top position, a stop O<9> on the rod B<3> connected to the ram acts through a stop O<8> and rod O<7> to move the lever O into engagement with the trigger M<7>. When the apparatus is to act with reference to length of arm stroke, the spring N<3> is so tansioned as to lock the valve M<1>, and the stop O<9> acts on a lever M<13> to release the trigger at the end of the power stroke. Manual control at any time is obtained by means of a shaft P provided with cams P<2>, P<3>. The pump used in any of the forms may be operated by means comprising a shaft Q, Fig. 10, on which is a slidable bush T with an eccentric periphery, and with a helical groove T' engaged by, a member U<1> on an eccentric ring U. A sleeve W held on the ring U has an arm W<1> passing through an oscillating member X and operating the pump. As the resistance of the pump increases, the bush T moves lengthwise against the resistance of an adjustable spring S, relative rotation between the eccentrics occurs and the stroke is diminished.